SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ade77c80ead204b9f44ccc68c7805644c0e4d15e909303b3cfb1c1ad1923a28' 
  AND token = 'H9V969uZ1LbJW7OqQ5B+MhanCfymxvRJmdgKEd/7T+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}